Susan,

I don't know what part of the country that you're working in, but 
"frost spalling" is a relatively common phenomenon ...

Essentially, moisture gets into the porous fabric of the pottery and 
it splits the pottery when it freezes during the winter.  It 
certainly does not happen all the time, but it does occur with some 
regularity.  Sometimes just the glaze spalls off the fabric, but the 
fabric itself can split.

Mark


>Nov. 10, 2010
>
>Hello all,
>
>I have a site with several sherds of transferware that are split so 
>that there is a transferware / glazed surface on one side and the 
>paste interior on the other side.  
>
>This makes them about 1/8 inch thick.  They tend to be about 1 inch 
>long, and about 3/4 inch wide. 
>
>The edges are not shaped; in "plan" view the pieces are 
>miscellaneously trapezoidal. 
>
>In appearance they somewhat remind me of porcelain pin 
>trays/childrens toy tea trays that are decorated and glazed on the 
>top and bisque on the bottom, except these transfer pieces are not 
>smoothly finished on the bottom ("bisque") like the porcelain items 
>are. 
>
>I do not think these were made intentionally.
>
>I've not seen so many of these at one site before.  Has anyone 
>knowledge of what did this?
>
>Thanks every one,
>
>S. Walter


-- 

Mark C. Branstner, RPA
Historic Archaeologist

Illinois State Archaeological Survey
Institute of Natural Resource Sustainability
University of Illinois at Urbana-Champaign
209 Nuclear Physics Lab, MC-571
23 East Stadium Drive
Champaign, IL 61820

Phone: 217.244.0892
Fax: 217.244.7458
Cell: 517.927.4556
[log in to unmask]


When you think of that perfect retort five minutes after the 
conversation is over -  that's when you're:

  "... bursting with the belated eloquence of the inarticulate ..."

Edith Wharton in the "The Age of Innocence"